Evolving brain function and connectivity patterns during mentalizing in children and adults.

Mentalizing, the ability to infer others' thoughts and intentions, relies on a network of brain regions whose functional connectivity changes across development. While prior research has focused on adults, little is known about task-based functional connectivity in this network during development. We use fMRI to examine mentalizing-related activation and task-based connectivity in 181 participants (80 children aged 6-14; 101 adults aged 20-61). Analyses assess age-related changes in activation and connectivity, and test whether connectivity mediates the relationship between age and mentalizing ability across neurofunctional groups. Adults outperform children in mentalizing accuracy, though children show age-related improvements. Activation patterns are largely overlapping across age groups, involving core regions such as the temporoparietal junction, precuneus, and medial prefrontal cortex. Connectivity analyses reveal that children show stronger local (frontal-frontal, posterior-posterior) connections, with increasing long-range (frontal-posterior) connectivity with age. Adults exhibit a more integrated network, though connectivity declines with age. Connectivity strength follows a quadratic trajectory, peaking in early adulthood (~ 32 years). Importantly, connectivity mediates the age-mentalizing relationship in children, but not in adults. These findings suggest a shift from local to distributed mentalizing network connectivity across development, followed by age-related decline, shedding light on lifespan changes in social cognition.